Antenna system



March 11, 1930. CONRAD 1,750,347

ANTENNA SYSTEM Filed June 1, 1925 WITNESSES: INVENTOR 4 5: 7 '4 Evin/4 Con/ad (ATTORNEY Patented Mar. 11, 1930 UNITED STATES PATENT ()F-FICEV FRANK CONRAD, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC 8:; MANUFACTURING COIEPANY, A CORPORATION OF PENNSYLVANIA ANTENNA SYSTEM Application filed June 1,

Myinvention relates to radio signalling systems and particularly to systems for the radiation of high-frequency energy. An object of my invention is to provide means associated with an oscillation radiator for preventing the radiation of frequencies different from that of the fundamental wave frequency. v I

Another object of my invention is to provide means for removing harmonic frequencies from an oscillation radiating circuit.

Another object of my invention is to pro vide means for reducing the transfer of harmonic frequency energy from an oscillation generator to an oscillation radiator, and means combined therewith for draining off such harmonic frequency energy as is not held back by the preventive means.

In the art of radio signalling it is common to provide a radio-frequency oscillation generating means and an oscillation radiating means electrically coupled thereto. It is also common to utilize an aerial and counterpoise construction with a conductive connection therebetween. In my copending application, Ser'al No. 7 57 ,581, filed December 23, 192i, Patent No. 1,652,516, December 13, 1927, and assigned to the WVestinghouse Electric and Manufacturing Company, I disclose a radio signalling system comprising an aerial and counterpoise as a radiator system, an oscillation generating means and a conductive coupling therebetween comprising an impedance which has the property of transmitting mainly the fundamental frequency of the oscillation generator and shows an increasing impedance to harmonic frequencies proportion al to the changing frequency.

This conductive impedance coupling produces a marked increase in the purity of radiated frequency from t 1e radiator system.

My present invention combines additional means for further increasing the purity of radiated waves. It consists of a radio-frequency by-pass means or drain circuit to ground having a high impedance to the fundamental frequency and a much lower impedance to harmonic frequencies. It is connected to the conductive coupling upon the 1925. Serial No. 33,903.

radiator side' of the impedance. By means of this combination of impedance and drain circuit, I am able to radiate an oscillation frequency of such purity that the presence of harmonics is substantially imperceptible.

ther objects and structural detailsof my an inductance 9 and a pair of series condensers 11 and- 12 in parallel therewith, and an associated vacuum-tube triode 14:. A ground connection 24 is made to the mid-point tap of the coil 9. Energy for the oscillating circuit may be supplied by generator 15 and energy for the cathode by a second generator 16. Signal modulation of the generator may be obtained by means of a modulator triode 17 and a telephone transmitter 18 through the agency of the system of connections shown.

The conductor 3 serves as a coupling means between the oscillation generator 2 and the radiator 1. The conductor 3 has, inserted therein, an adjustable inductance 19 according to the details of the system of my pre vicusly mentioned disclosure. A parallel resonant circuit 21 is connected at a point intermediate the oscillation generator and the radiator 1. This circuit consists of an inductance 22 and a condenser 23.

in the operation of my invention, the oscillation generator 2 may be energized by the current sources 15 and 16, oscillations of suitable frequency may then be obtained in the oscillating system comprising the inductance 9 and the condensers 11 and 12 by suit able adjustment of the magnitude of the inductance and adjustment of the connections then be made by adjustment of the-inductance 7. 7

A. maximum transfer of energy from the generator to the radiator may then be obtained by reducing the amount of impedance i the inductor 19 until a pointis reached at rich the abstraction of energy from the osating circuit is as great as the generator le 14 will'supply. The filter trap 21 may then be connected to the coupling means 3 and its frequency adjusted to reject the fundamental frequency of the oscillation generaor 2. i

Under these conditions, theoscillation'generator 2 will produce a maximum amplitude of oscillation, at its fundamentalfrequency whicn may be accompanied 'by asubstantial iunount of"os'cillations at various harmonic frequencies. A maximum amount of energy at the fundamental frequency is "thentransferred to the radiator l-but a proportionately smaller amount of harmonic frequency energy is transferred past the inductor 19 because of its higher impedance tothe higher frequencies. a k i L Substantially no energy of] fundamental oscillation frequency passes through the drain circuit 21 because of the fact that the parallel resonantcircuit is tuned'to that frequency and offers an extremely'high impedance thereto, but a very large portion of the harmonic frequency energy which is able 'to pass through conductor 19 is accepted by the drain circuit 21 and by-passed to ground, thereby-causing substantially all of the fundamental frequency energy to be transferred to the radiator system 1. Simultaneously a small amount of harmonic frequency energy is allowed to pass to the radiator system.

By this means, I am enabled to obtain a greater purity of oscillation frequency in an oscillation radiating system than has been obtainable by any prior system.

iVhile I have shown but a single embodiment of my invention in the accompanying drawing, it is capable of various changes and modifications therefrom without departing from the spirit thereof and it is desired therefore that only such limitations shall be imposed thereon as are imposed by the prior art or indicated in the appended claims.

I claim as my invention:

1. A radio signalling system comprising a aerial, a counterpoise, a connection therebetween comprising an inductor and a lead ire, an oscillation generating means, a transfer channel therebetween comprising a second lead wire, connected to said first mentioned lead Wire and to said generator and a lumped impedance interposed therein, and a ground connection to said transfer channel having a high impedance to the fundamental frequency of said generator, and a low impedance to allother frequencies.

2;"A radio signalling system comprising an aerial a counterpoise, a connection therebetween comprising an inductor and a lead wire, an oscillation generating means, atransfer channel therebetween comprising a second lead wire, connected to said first mentioned lead wire and to said generator and lumped impedance :inte-rposed therein, and a ground connection to said transfer channel having a high'impedance to the frequency of radiation of said aerial.

3. In combination, a plurality of elevated conductors insulated from ground and interconnected through a tuning inductor, an oscillation generator, a single connection be-- tween the generator and the said conductors in which Voltage and current phenomenaare substantially in phase, and means associated with said single connection for by-passing to ground frequerrcies other than the fundamental'frequency-of said generator, thereby preventing the radiation of undesired frequen mes.

a 4:, Ara'dio transmitting system comprising a radiation structure constituted by an an tenna and a counterpoise connected thereto, an oscillation'generator having an output circuit, a single insulated conductive connection bet-ween said output circuit and said radiation structure, means associated with said connection for rejecting oscillations of undesired frequencies, and 'means interposed between said rejecting means and said radiation structure for by-passing to ground such of said undesired oscillations as may pass said rej acting means." i In testimony whereof, I have hereunto subscribed my-name this 21st day of May, 1925.

FRANK CONRAD. 

